1. Field of the Invention
The present invention relates generally to apparatus for automatically stacking and unitizing articles. More particularly, the invention relates to such an apparatus which is specially adapted to both stack and unitize easily compressible articles, such as bundles of insulation.
2. Description of Related Art
Apparatus for automatically stacking and unitizing various articles are known in the art. Examples of such apparatus, generally referred to as robotic palletizers or unitizers, are disclosed in U.S. Pat. Nos. 4,995,224, 5,005,335 and 5,046,303, all commonly owned with the present application. These apparatus generally include a moveable hand assembly which picks the articles to be stacked off of an infeed conveyor and places them in a preselected orientation on a turntable. Once a single layer of articles is formed on the turntable, subsequent layers are formed on top of each other until a preselected stack height is reached. The apparatus may also include means for wrapping the articles on the turntable, either during the formation of individual layers or once the entire stack is formed, to thereby unitize the entire stack.
The stacking and unitizing of easily compressible products, such as bundles of insulation, poses special problems, however. Since they are dimensionally unstable, they are difficult to grip with conventional hand assemblies. In addition, since these articles are easily compressible, they are difficult to stack into multiple layers.